US5740703A

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Info

Publication number: US5740703A
Application number: US08/579,119
Authority: US
Inventors: Robert G. Perry
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-12-27
Filing date: 1995-12-27
Publication date: 1998-04-21
Anticipated expiration: 2015-12-27

Abstract

A tong apparatus is provided for gripping a pipe. The apparatus includes a support having a track, a first positive stop, and a second positive stop. The apparatus also includes a jaw assembly having a base slidably coupled to the track of the support. The jaw assembly includes a cylinder having a movable piston. The cylinder is rigidly coupled to the base. The jaw assembly also includes a clamp for gripping the pipe. The clamp has a first jaw coupled to the movable piston and a second jaw coupled to the base. The first jaw has at least one stop located between the first and second positive stops of the support so that when the piston is extended from the cylinder the first jaw initially moves toward the second jaw until the first jaw engages the first positive stop. Further extension of the piston causes the base, the cylinder, and the second jaw to move relative to the support toward the first jaw until the second jaw engages the pipe to grip the pipe and prevent rotation of the pipe relative to the jaw assembly.

Description

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to an improved power wrench apparatus. More particularly, the present invention relates to a power wrench or tong apparatus and a cooperating backup wrench or tong apparatus which include positive sliding clamps for breaking connections between links of pipe as the pipe is being removed from the ground.

It is well known to push a rod or pipe through the ground with a drilling rig from one location to another predetermined location beneath the surface of the ground. For example, a pipe may be pushed under a road from one side of the road to another without creating a trench in the road. Generally speaking, apparatus for directing forward movement of a pipe through the ground beneath the surface of the ground are known in the art. Drilling rigs are also used to drill into the ground for oil wells or the like. Typically, these drilling rigs rotate the pipe in a counterclockwise direction or a clockwise direction to install or remove pipe from the ground.

Making and breaking apparatus are known for making up or breaking out joints between adjacent pipes which are driven into the ground with known drilling rigs. As the pipe is being removed from the ground, joints between adjacent sections must be loosened to permit the next section of pipe to be removed from the ground.

The power wrench apparatus of the present invention includes two separate wrenches or tongs operating in conjunction with each other. A backup tong is provided to grip and hold a lower section of pipe which extends into the ground stationary. A power tong is provided to grip and rotate an upper section of pipe which is connected to the lower section of pipe in the ground. While the backup tong prevents rotation of the lower length of pipe, the power tong grips and rotates the upper section of pipe to break the joint between the upper and lower pipe sections.

Clamps or jaws of the power tong and the backup tong are configured to enter elongated slots formed in supports to permit limited sliding movement of the jaw assemblies relative to the supports. Therefore, the entire jaw assembly can slide relative to the support. The power tong and the backup tong both include a pair of positive stops to limit movement of the jaw assemblies. These positive stops provide improved positioning of the pipes relative to the power tong and backup tong while still permitting the jaws to slide relative to the supports.

According to one aspect of the present invention, a tong apparatus is provided for gripping a pipe. The apparatus includes a support having a track, a first positive stop, and a second positive stop. The apparatus also includes a jaw assembly having a base slidably coupled to the track of the support. The jaw assembly includes a cylinder having a movable piston. The cylinder is rigidly coupled to the base. The jaw assembly also includes a clamp for gripping the pipe. The clamp has a first jaw coupled to the movable piston and a second jaw coupled to the base. The first jaw has at least one stop located between the first and second positive stops of the support so that when the piston is extended from the cylinder the first jaw initially moves toward the second jaw until the first jaw engages the first positive stop. Further extension of the piston causes the base, the cylinder, and the second jaw to move relative to the support toward the first jaw until the second jaw engages the pipe to grip the pipe and prevent rotation of the pipe relative to the jaw assembly.

In the illustrated embodiment, the base of the jaw assembly includes first and second flanges located in the track of the support. The support includes a pair of spaced apart side walls. Each side wall is formed to include an elongated groove to define the track.

Also in the illustrated embodiment, the first and second jaws are formed to include a plurality of teeth for gripping the pipe. The plurality of teeth on the first and second jaws are formed by removable wedge plates.

In the illustrated embodiment, the first and second jaws each include an inwardly projecting retention finger to block movement of the pipe away from the first and second jaws. The apparatus also includes a bearing coupled to the support for receiving the pipe therethrough. The first positive stop is formed by a removable jaw guide coupled to the support.

Retraction of the piston initially causes the first jaw to move away from the pipe until the at least one stop on the first jaw engages the second positive stop of the support. Further retraction of the piston causes the base, the cylinder, and the second jaw to move relative to the support away from the first jaw so that the second jaw is disengaged from the pipe.

In one illustrated embodiment, the apparatus further includes a frame. The support is pivotably coupled to the frame. A pair of drive cylinders have movable pistons which are coupled to the support to rotate the support relative to the frame after the first and second jaws grip the pipe. The drive pistons are pivotably coupled to the support and the drive cylinders are pivotably coupled to the frame.

The frame and the support are each formed to include an arcuate groove. The apparatus includes an arcuate bearing member extending between the arcuate groove of the frame and the arcuate groove of the support to provide a bearing for pivotably coupling the support to the frame. In the illustrated embodiment, the bearing member and the arcuate grooves each have a semicircular shape.

According to another aspect of the invention, a break down tong apparatus is provided for breaking loose a connection between a first joint portion and a second joint portion connecting a first pipe and a second adjacent pipe, respectively. The apparatus includes a frame, and a backup tong including a first support rigidly coupled to the frame. The first support includes first and second positive stops. The backup tong also includes a first jaw assembly having a first base slidably coupled to the first support. The first jaw assembly includes a first cylinder having a first movable piston. The first cylinder is rigidly coupled to the first base. The first jaw assembly also includes a first clamp for gripping the first pipe. The first clamp has a first jaw coupled to the first movable piston and a second jaw coupled to the first base. The first jaw has at least one stop located between the first and second positive stops of the first support so that when the first piston is extended from the first cylinder the first jaw initially moves toward the second jaw until the first jaw engages the first positive stop of the first support. Further extension of the first piston causing the first base, the first cylinder, and the second jaw to move relative to the first support toward the first jaw until the second jaw engages the first pipe to grip the first pipe and prevent rotation of the first pipe relative to the first jaw assembly.

The break down tong apparatus also includes a power tong having a second support pivotably coupled to the frame adjacent the backup tong. The second support includes first and second positive stops. The power tong also includes a second jaw assembly having a second base slidably coupled to the second support. The second jaw assembly includes a second cylinder having a second movable piston. The second cylinder is rigidly coupled to the second base. The second jaw assembly also includes a second clamp for gripping the second pipe. The second clamp has a third jaw coupled to the second movable piston and a fourth jaw coupled to the second base. The third jaw has at least one stop located between the first and second positive stops of the second support so that when the second piston is extended from the second cylinder the third jaw initially moves toward the fourth jaw until the third jaw engages the first positive stop of the second support. Further extension of the second piston causing the second base, the second cylinder, and the fourth jaw to move relative to the second support toward the third jaw until the fourth jaw engages the second pipe to grip the second pipe and prevent rotation of the second pipe relative to the second jaw assembly.

The break down tong apparatus further includes dual drive cylinders coupled to the frame. The drive cylinders each have a drive piston coupled to the second support to rotate the power tong relative to the frame while the second jaw assembly is engaged with the second joint portion, thereby rotating the second joint portion relative to the first joint portion to break the connection between the first joint portion and the second joint portion.

In the illustrated embodiment, a bearing surrounds the pipe. The bearing is located adjacent the backup tong on an opposite side of the backup tong from the power tong. The drive pistons preferably rotate the power tong about 20° relative to the base to break the connection between the first joint portion and the second joint portion.

The first and second jaws each include an inwardly projecting retention finger to block movement of the pipe away from the first and second jaws. In the illustrated embodiment, the first positive stops are formed by a first removable jaw guide coupled to the first support and a second removable jaw guide coupled to the second support.

According to yet another embodiment of the present invention, a power tong apparatus is provided for gripping and rotating a pipe. The apparatus includes a frame having first and second frame members which are formed to include arcuate grooves, and a support having first and second support plates. Each of the first and second support plates have an outer side wall formed to include an arcuate groove aligned with the arcuate grooves in the first and second frame members. The apparatus also includes first and second arcuate floating bearing members extending between the arcuate grooves of the first and second support plates and the arcuate grooves of the first and second frame members to pivotably couple the support to the frame. The apparatus further includes a jaw assembly coupled to the first and second support members for gripping the pipe, and a drive mechanism coupled to the support for rotating the support relative to the frame.

In one illustrated embodiment, the arcuate grooves extend over a greater arcuate angle than the first and second floating bearing members. In another embodiment, the arcuate grooves and the first and second bearing members are all circular in shape.

Also in the illustrated embodiment, the drive mechanism includes a first drive cylinder having a first piston pivotably coupled to the first support plate. The drive mechanism also includes a second drive cylinder having a second piston pivotably coupled to the second support plate.

Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figures in which:

FIG. 1 is a perspective view of a drilling rig which includes the power wrench apparatus of the present invention and power pipe loader;

FIG. 2 is an exploded perspective view illustrating details of the power wrench apparatus of the present invention;

FIG. 3 is top plan view, with portions broken away, of the assembled power wrench apparatus of FIG. 2;

FIG. 4 is a sectional view taken alonglines 4--4 of FIG. 3 illustrating the configuration of the backup tong apparatus with the jaws of the clamp in a fully open position when a piston of the backup cylinder is in a retracted position;

FIG. 5 is a sectional view similar to FIG. 4 in which the backup piston has been extended until the first jaw engages the pipe or a fixed positive stop;

FIG. 6 is a sectional view similar to FIGS. 4 and 5 illustrating further extension of the piston to move the backup jaw assembly and the second jaw into engagement with the pipe;

FIG. 7 is a sectional view taken alonglines 7--7 of FIG. 3 illustrating details of the first jaw, a removable guide, and positive stops of the jaw assembly; and

FIG. 8 is a sectional view taken along lines of 8--8 of FIG. 3 illustrating operation of the power tong apparatus to grip and rotate a pipe to break a joint connection between adjacent sections of pipe.

DETAILED DESCRIPTION OF DRAWINGS

Referring now to the drawings, FIG. 1 illustrates drilling rig 10 including amain drive 12 having a threaded drive head 14.Main drive unit 12 is driven back and forth overframe 16.Main drive unit 12 rotates threaded drive head 14 to drive

pipe sections

24 and 26 into theground 18. Afterlower pipe 26 is driven into theground 18,pipe 24 must be connected to a threaded end 32 (shown in FIG. 3) oflower pipe 26 in order to continue driving the pipe into the ground. Main drive 12 rotates drive head 14 and pushes the pipe in the direction ofarrow 20 to move the pipe into the ground. Pipe is also removed from theground 18 usingmain drive 12 which rotates and pulls the pipe in the direction of arrow 22.

In FIG. 1, anupper pipe section 24 is connected to threaded drive 14 and alower pipe section 26 is coupled toupper pipe 24 by a joint which includes a male joint portion 30 onupper pipe 24 and a femalejoint portion 32 onlower pipe 26. In order to remove theupper pipe 24 fromlower pipe 26, the joint betweenupper pipe 24 andlower pipe 26 must be broken. Although a portable drilling rig 10 is illustrated, it is understood that any type of drilling rig can be used in accordance with the present invention. Drilling rig 10 can be positioned in a horizontal position as illustrated in FIG. 1 or in a vertical position for drilling straight down into the ground.

A break downtong apparatus 34 is provided to break the connection betweenjoint portions 30 and 32 as the pipe is removed from the ground. Break downtong apparatus 34 includes abackup tong apparatus 36 which gripslower pipe 26 and holdslower pipe 26 stationary. Break downtong apparatus 34 also includes apower tong apparatus 38 which grips and rotates theupper pipe 24 to break the connection between upper and lowerjoint sections 30 and 32. Break downtong apparatus 34 also includes abearing 42 coupled to frame 16 adjacentbackup tong apparatus 36.Bearing 42 surroundslower pipe 26 to help align and stabilize the pipe as the pipe is driven into the ground to reduce wear and tear on thebackup tong apparatus 36 andpower tong apparatus 38 as the pipe is driven into theground 18.

The preferred embodiment of the break downtong apparatus 34 is designed for use with apower pipe loader 43 which removes and stacks the pipes. It is understood that any type of conventional pipe loader may be used with the break downtong apparatus 34 of the present invention. In addition, the break down tong apparatus can be designed for standard end-loading of the pipes as discussed below.

Further details of the break downtong apparatus 34 are illustrated in FIGS. 2 and 3. Break downtong apparatus 34 includes three spaced apart, fixed supports 44, 46, and 48 which are rigidly coupled tobase 16.Support 44 includes aU-shaped opening 50 and anextended groove 52.Support 46 includes a similarU-shaped opening 54 and asimilar groove 56 which facesgroove 52 formed insupport 44. Anopposite side wall 58 ofsupport 46 is formed to included asemi-circular groove 60.Support 48 is also formed to include aU-shaped aperture 62. Asemi-circular groove 64 is formed inside wall 66.

The

U-shaped apertures

50, 54, and 62 permit top loading of pipes into the break downtong apparatus 34 fromloader 43. It is understood, however, that the

supports

44, 46, and 48 could be formed with only a central aperture so that the pipes are loaded from an end of the break downtong apparatus 34 adjacent thesupport 48. In addition, the

U-shaped apertures

50, 54, and 62 may be aligned at any desired angle (360°) to permit loading of the pipes from any orientation.

Bearing 42 is coupled to support 44 bysuitable fasteners 68.Bearing 42 surrounds thelower pipe 26 to help align and stabilize thelower pipe 26 as it is driven into and pulled from the ground to reduce wear and tear on thebreakdown tong apparatus 34.Breakup tong apparatus 36 includes a positive slidingjaw assembly 70 having abase 72.Base 72 includes

opposite flanges

74 and 76 configured to slide within

grooves

52 and 56 formed in

supports

44 and 46, respectively.Base 72 also includes an upwardly extendingjaw 78 having apipe retention finger 80 extending therefrom.Base 72 includes a fixedsupport wall 82. Acylinder 84 is coupled to supportwall 82 bysuitable fasteners 86. Anotherjaw 88 is coupled to apiston 90 ofcylinder 84.Jaw 88 includes apipe retention finger 89 and stops 92 extending away from opposite sides of thejaw 88.Removable teeth 94 are coupled tosecond jaw 88 as discussed below.

AU-shaped jaw guide 96 is coupled between

support

44 and 46 bysuitable fasteners 98.Fasteners 98 extend throughapertures 100 and into threadedapertures 102 ofjaw guide 96.Jaw assembly 70 is positioned within the track defined by

grooves

52 and 56. The stops 92 onjaw 88 are located between firstpositive stops 104 formed on

supports

44 and 46 and second positive stops defined byedges 106 ofjaw guide 96. The position of thejaw guide 96 is illustrated in FIG. 7. A detailed discussion of the positive sliding clamp is provided below.

Power tong apparatus 38 includes a pair ofrotating plates 108 and 110.Plates 108 and 110 include

U-shaped apertures

112 and 114 respectively.Plate 108 is formed to included a semi circular grove inside wall 116. Asemi-circular bearing member 118 extends between thegroove 60 and the semi-circular groove (not shown) formed inplate 108 to provide a first bearing member for thepower tong apparatus 38.

Plate 110 is formed to include asemi-circular groove 120 inside wall 122. Asemi-circular bearing member 124 extends betweengroove 120 of plate 110 and groove 64 ofsupport 48 to provide a second bearing for thepower tong apparatus 38.

Bearing members

118 and 124 are configured to float within

arcuate grooves

60 and 120, 64 to permit rotation ofplates 108 and 110 relative to

supports

46 and 48. Illustratively, the

arcuate grooves

60, 120 and 64 extend over a 210° angle, while bearing

members

118 and 124 extend over only a 180° angle.

Although the first and second bearings are illustrated as semi-circular bearings, it is understood that these bearings may be circular bearing members extending completely around the pipe which extend between circular grooves that completely surround the pipe formed in the

supports

46 and 48 andplates 108 and 110 in another embodiment of the present invention. In other words, the arcuate grooves and bearing members may all be 360°. This embodiment still permits the bearing members to float so that no welding is required. The bearing

members

118 and 124 provide a large bearing surface for pivotal movement of thepower tong 38.

Power tong apparatus 38 includes ajaw assembly 130.Jaw assembly 130 includes a base 132 having an upwardly extendingjaw 134.Removable wedges 136, which provide the jaw teeth, are situated withinslots 138 ofjaw 134. Anend cap 140 is then secured over thewedges 136 byfasteners 142.Jaw assembly 130 also includes acylinder 144 coupled to a fixedsupport 146 ofbase 132 bysuitable fasteners 148.Cylinder 144 includes amovable piston 150. Ajaw 152 is coupled topiston 150 by apin 154.

Plates 108 and 110 are formed to include

extended grooves

126 and 128, respectively.

Opposite flanges

156 and 158 ofbase 132 are located within

grooves

126 and 128, respectively, ofplates 108 and 110 so that thejaw assembly 130 can slide relative toplates 108 and 110.

Stops 160 are formed onsecond jaw 152. Thestops 160 are located between firstpositive stops 162 formed onplates 108 and 110 and aU-shaped jaw guide 164 which includes stops 166.Jaw guide 164 is secured toplates 108 and 110 byfasteners 168 which extend throughapertures 170 and into threadedapertures 172 ofjaw guide 164.

The

bearings

118 and 124 permit rotation of the powertong jaw assembly 130 andplates 108 and 110 relative to

supports

46 and 48. A pair ofdrive cylinders 174 are used to rotate thejaw assembly 130 to break a joint connection between adjacent sections of pipe.Pistons 176 ofcylinders 174 are pivotably coupled toplates 108 and 110 atlocations 178 byfasteners 179.Cylinders 174 are pivotably coupled tobase 16 bysuitable connectors 180 andfasteners 181. Therefore, extension ofpistons 176 causes rotation ofplates 108 and 110 andjaw assembly 130 to break the joint connection as discussed below. The dualpivoting drive cylinders 174 have a close profile arrangement. In other words, thecylinders 174 do not extend beyond the profile of the

cylinders

84 and 144 of the

jaw assemblies

70 and 130, respectively. Therefore, thedual drive cylinders 174 are an improvement over conventional single drive cylinders for rotating a power tong.

Cylinders

84, 144, and 174 are coupled to a suitable hydraulic controller (not shown). The hydraulic controller supplies hydraulic fluid to the

cylinders

84, 144, and 174 to extend and retract the

pistons

90, 150, and 176, respectively, in a conventional manner.

FIGS. 3-6 disclose the position of apipe locating boss 182. A locatingboss 182 is positioned on both thebackup tong 36 and thepower tong 38.Boss 182 prevents the

pipes

24 and 26 from dropping beneath the supports and jamming during insertion or removal of the

pipes

24 and 26.

FIGS. 4-6 illustrate operation of the positive sliding clamp of the backup tongs and power tongs of the present invention. In FIG. 4,teeth 95 ofjaw 78 andteeth 94 ofjaw 88 are all spaced apart frompipe 26.

Retention fingers

80 and 89 are coupled to

jaws

78 and 88, respectively, away frompipe 26. FIG. 4 illustrates thepiston 90 ofcylinder 84 in a retracted position so that thestops 92 onjaw 88 engagestops 104 formed on

supports

44 and 46.

Aspiston 90 is first extended in the direction ofarrow 186 in FIG. 5,jaw 88 moves in the direction ofarrow 186 towardpipe 26 while thebase 72 andjaw 78 remain in the position of FIG. 4.Jaw 88 continues to move in the direction ofarrow 186 until eitherteeth 94 ofjaw 88 engagepipe 26 or until thestops 92 on thejaw 88 engage thestops 106 ofjaw guide 96. Therefore, stops 106 onjaw guide 96 provide positive stops for preventing further movement ofjaw 88 in the direction ofarrow 186 caused by extension of thepiston 90.Stops 106 are positioned to alignpipe 26 substantially in the center of the U-shaped apertures. Therefore, thepositive stops 106 provide accurate positioning forpipe 26 during clamping of the

jaws

78 and 88. Jaw guide 96 also prevents movement ofjaw 88 in the direction ofarrow 187 of FIG. 5. FIG. 5 illustratesjaw 88 in contact with thepipe 26 after extension of thepiston 90.

Afterjaw 88 hits thestops 106 onjaw guide 96, further extension ofpiston 90 causes thebase 72, thefirst jaw 78, and thecylinder 84 move in the direction ofarrow 188 in FIG. 6 so that theteeth 95 ofjaw 78 move into engagement withpipe 26.

Therefore, thejaw assembly 70 is permitted to slide relative to

supports

44 and 46. However, the first set ofpositive stops 104 and the second set ofpositive stops 106 provide a positive sliding clamp for grippingpipe 26.

During retraction of the

jaws

78 and 88 frompipe 26,piston 90 is retracted untilstops 92 onjaw 88 engagestops 104 on

supports

44 and 46. Further retraction of the piston causesbase 72, thejaw 78, andcylinder 84 to move in the direction ofarrow 186 back to the space apart position illustrated in FIG. 4 to release thepipe 26.

The gripping positive sliding clamp defined by

jaws

134 and 152 of powertong jaw assembly 130 works in a manner identical tojaw assembly 70 of the back uptong apparatus 36. Once theteeth 136 ofjaw 134 and the teeth 194 ofjaw 152 engage and grip thepipe 24, drivecylinders 174 are actuated to extendpistons 176. Full extension ofpistons 176 is illustrated in FIG. 8. Therefore, thepistons 176 rotate theplates 108 and 110, thebase 132, and the first and

second jaws

134 and 152 in the direction ofarrow 190 to break a connection between the threaded joint connection 30 ofupper pipe 24 and femalejoint section 32 oflower pipe 26.

After the joint connection is broken,pistons 176 are retracted to rotate the power tongs in the direction ofarrow 192.Piston 150 ofjaw assembly 130 is also retracted to move

jaws

134 and 152 away frompipe 24. Control tomain drive 12 is then actuated to continue rotation of drive head 14 about 10 revolutions to uncouple theupper pipe section 24 from thelower pipe section 26.Cylinder 150 is then actuated to extend

jaws

152 and 134 again to engage thepipe 24. Main drive 12 then actuates the drive head 14 to break drive head 14 away from an upper end ofpipe 24. This permitspipe 24 to be removed.

Piston 90 ofcylinder 84 is then retracted to release thelower pipe 26 from

jaws

78 and 88. Main drive 12 is then moved in the direction ofarrow 20 in FIG. 1 so that the drive head 14 can be coupled to the lowerjoint section 32 to pulllower pipe 26 out of theground 18.

Although the invention has been described in detail with reference to a certain preferred embodiment, variations and modifications exist within the scope and spirit of the present invention as described and defined in the following claims.

Claims

What is claimed is:

1. A tong apparatus for gripping a pipe, the apparatus comprising:

a support having a track, a first positive stop, and a second positive stop; and

a jaw assembly having a base slidably coupled to the track of the support, the jaw assembly including a cylinder having a movable piston, the cylinder being rigidly coupled to the base, the jaw assembly also including a clamp for gripping the pipe, the clamp having a first jaw coupled to the movable piston and a second jaw coupled to the base, the first jaw having at least one stop located between the first and second positive stops of the support so that when the piston is extended from the cylinder the first jaw initially moves toward the second jaw until the first jaw engages the first positive stop, further extension of the piston causing the base, the cylinder, and the second jaw to move relative to the support toward the first jaw until the second jaw engages the pipe to grip the pipe and prevent rotation of the pipe relative to the jaw assembly and wherein retraction of the piston initially causes the first jaw to move away from the pipe prior to movement of the second jaw.

2. The apparatus of claim 1, wherein the support includes a pair of spaced apart side walls, each side wall being formed to include an elongated groove to define the track, and the base of the jaw assembly includes first and second flanges located in the elongated grooves of the support.

3. The apparatus of claim 1, wherein the first and second jaws are formed to include a plurality of teeth for gripping the pipe, the plurality of teeth on the first and second jaws being formed by removable wedge plates.

4. The apparatus of claim 1, wherein the first and second jaws each include an inwardly projecting retention finger to block movement of the pipe away from the first and second jaws.

5. The apparatus of claim 1, wherein the support is formed to include a U-shaped aperture for permitting loading of the pipes.

6. The apparatus of claim 1, wherein the first positive stop is formed by a removable jaw guide coupled to the support.

7. The apparatus of claim 1, wherein retraction of the piston initially causes the first jaw to move away from the pipe until the at least one stop on the first jaw engages the second positive stop of the support, further retraction of the piston causing the base, the cylinder, and the second jaw to move relative to the support away from the first jaw so that the second jaw is disengaged from the pipe.

8. The apparatus of claim 1, further comprising a frame, the support being pivotably coupled to the frame, and dual drive cylinders, each drive cylinder having a movable piston coupled to the support to rotate the support relative to the frame after the first and second jaws grip the pipe.

9. The apparatus of claim 8, wherein the support is formed by first and second spaced apart plates, the drive pistons being pivotably coupled to the plates and the drive cylinders being pivotably coupled to the frame.

10. The apparatus of claim 8, wherein the frame and the support are each formed to include an arcuate groove, and further comprising an arcuate bearing member extending between the arcuate groove of the frame and the arcuate groove of the support to provide a floating bearing for pivotably coupling the support to the frame.

11. The apparatus of claim 10, wherein the arcuate grooves extend over a greater angle than the floating bearing member.

12. The apparatus of claim 10, wherein the arcuate grooves and the floating bearing member all extend a full 360°.

13. A break down tong apparatus for breaking loose a connection between a first joint portion and a second joint connecting a first pipe and a second adjacent pipe, respectively, the apparatus comprising:

a frame;

a backup tong including a first support rigidly coupled to the frame, the first support including first and second positive stops, the backup tong also including a first jaw assembly having a first base slidably coupled to the first support, the first jaw assembly including a first cylinder having a first movable piston, the first cylinder being rigidly coupled to the first base, the first jaw assembly also including a first clamp for gripping the pipe, the first clamp having a first jaw coupled to the first movable piston and a second jaw coupled to the first base, the first jaw having at least one stop located between the first and second positive stops of the first support so that when the first piston is extended from the first cylinder the first jaw initially moves toward the second jaw until the first jaw engages the first positive stop of the first support, further extension of the first piston causing the first base, the first cylinder, and the second jaw to move relative to the first support toward the first jaw until the second jaw engages the first pipe to grip the first pipe and prevent rotation of the first pipe relative to the first jaw assembly;

a power tong including a second support pivotably coupled to the frame adjacent the backup tong, the second support including first and second positive stops, the power tong also including a second jaw assembly having a second base slidably coupled to the second support, the second jaw assembly including a second cylinder having a second movable piston, the second cylinder being rigidly coupled to the second base, the second jaw assembly also including a second clamp for gripping the second pipe, the second clamp having a third jaw coupled to the second movable piston and a fourth jaw coupled to the second base, the third jaw having at least one stop located between the first and second positive stops of the second support so that when the second piston is extended from the second cylinder the third jaw initially moves toward the fourth jaw until the third jaw engages the first positive stop of the second support, further extension of the second piston causing the second base, the second cylinder, and the fourth jaw to move relative to the second support toward the third jaw until the fourth jaw engages the second pipe to grip the second pipe and prevent rotation of the second pipe relative to the second jaw assembly;

wherein retraction of either of the first or second cylinders initially cause the respective first or third jaw away from the pipe prior to the second or fourth jaw; and

dual drive cylinders coupled to the frame, the dual drive cylinders each having a drive piston coupled to the second support to rotate the power tong relative to the frame while the second jaw assembly is engaged with the second joint portion, thereby rotating the second joint portion relative to the first joint portion to break the connection between the first joint portion and the second joint portion.

14. The apparatus of claim 13, further comprising a bearing surrounding the pipe, the bearing being located adjacent the backup tong on an opposite side of the backup tong from the power tong.

15. The apparatus of claim 13, wherein the first and second jaws each include an inwardly projecting retention finger to block movement of the pipe away from the first and second jaws.

16. The apparatus of claim 13, wherein the first positive stops are formed by a first removable jaw guide coupled to the first support and a second removable jaw guide coupled to the second support.

17. The apparatus of claim 13, wherein the drive pistons are pivotably coupled to the second support and the drive cylinders are pivotably coupled to the frame.

18. The apparatus of claim 13, wherein the frame and the second support are each formed to include an arcuate groove, and further comprising an arcuate floating bearing member extending between the arcuate groove of the frame and the arcuate groove of the second support to provide a bearing for pivotably coupling the second support to the frame.

19. A power tong apparatus for gripping and rotating a pipe, the apparatus comprising:

a frame having first and second frame members which are formed to include arcuate grooves;

a support having first and second support plates, each of the first and second support plates having an outer side wall formed to include an arcuate groove aligned with the arcuate grooves in the first and second frame members;

first and second arcuate floating bearing members extending between the arcuate grooves of the first and second support plates and the arcuate grooves of the first and second frame members to pivotably couple the support to the frame;

a jaw assembly coupled to the first and second support members for gripping the pipe; and

a drive mechanism coupled to the support for rotating the support relative to the frame.

20. The apparatus of claim 19, wherein the arcuate grooves extend over a greater arcuate angle than the first and second floating bearing members.

21. The apparatus of claim 19, wherein the arcuate grooves and the first and second bearing members are all circular in shape.

22. The apparatus of claim 19, wherein the drive mechanism includes a first drive cylinder having a first piston pivotably coupled to the first support plate and a second drive cylinder having a second piston pivotably coupled to the second support plate.

23. The apparatus of claim 19, wherein the jaw assembly includes a base slidably coupled to the first and second support plates, a cylinder having a movable piston, the cylinder being rigidly coupled to the base, the jaw assembly also including a clamp for gripping the pipe, the clamp having a first jaw coupled to the movable piston and a second jaw coupled to the base, the first jaw having at least one stop located between a first positive stop and a second positive stop formed on the support so that when the piston is extended from the cylinder the first jaw initially moves toward the second jaw until the first jaw engages the first positive stop, further extension of the piston causing the base, the cylinder, and the second jaw to move relative to the support toward the first jaw until the second jaw engages the pipe to grip the pipe and prevent rotation of the pipe relative to the jaw assembly.

24. A tong apparatus for gripping a pipe, the apparatus comprising:

a support having a track and a first positive stop; and

a jaw assembly having a base slidably coupled to the track of the support, the jaw assembly including a cylinder having a movable piston, the cylinder being rigidly coupled to the base, the jaw assembly also including a clamp for gripping the pipe, the clamp having a first jaw coupled to the movable piston and a second jaw coupled to the base, the first jaw having a stop configured to engage the first positive stop of the support so that retraction of the piston when the first and second jaws are engaged with the pipe initially causes the first jaw to move away from the pipe until the stop on the first jaw engages the first positive stop of the support, further retraction of the piston causing the base, the cylinder, and the second jaw to move relative to the support away from the first jaw so that the second jaw is disengaged from the pipe.

25. The apparatus of claim 24, wherein the support includes a second positive stop spaced apart from the first positive stop; the stop of the first jaw being located between the first and second positive stops so that extension of the piston from the cylinder when the first and second jaws are disengaged from the pipe initially moves the first jaw toward the second jaw until the first jaw engages the second positive stop, further extension of the piston causing the base, the cylinder, and the second jaw to move relative to the support toward the first jaw until the second jaw engages the pipe to grip the pipe and prevent rotation of the pipe relative to the jaw assembly.